Malcolm Guthrie opens his critique of Herbert Spencer's Data of Ethics by situating it as the third volume in a series that began with On Mr. Spencer's Formula of Evolution and On Mr. Spencer's Unification of Knowledge. He addresses his work to students who already possess an intimate knowledge of Spencer's system, not to the general reader. Guthrie's central contention is that whatever value Spencer's philosophy holds derives from a posteriori grounds, not from its a priori reliance on first principles. He singles out the transition from inorganic to organic as the most critical point in Spencer's system, upon which the practical value of the philosophy depends.

The Sociological Origin of Ethics

Guthrie argues that the origin and authority of ethics are found in sociology, not in biology or individual psychology. He writes that the main fact underlying all ethics is the existence of a society composed of subjective factors—beings with feelings and reasoning powers. The fundamental notion is the regulation of mutual conduct among these factors. Guthrie states, "It is the voice of the million against the voice of the unit which decides the duty of the unit." He emphasizes that ethical obligations arise from social pressure, which ensures that individual actions are not inimical to society's welfare and, secondarily, subservient to it. This pressure must not destroy the welfare of individuals, as that would undermine society's own objects.

Inverse Order of Inquiry

Guthrie proposes an inverse order of inquiry compared to Spencer. Instead of seeking ethical authority on individual or biological grounds and culminating in an ethical sociology, Guthrie advocates acknowledging the sociological origin and authority of ethics first, then understanding it through subordinate study of biological requirements and psychological growths. He contends that Spencer's mode of exposition suffers from this misordering. Ethical problems, Guthrie suggests, are worked out through societal growth and individual adjustments, not deduced from first principles. He notes that general rights and duties can be deduced as corollaries, but beyond these, ethical problems must be worked out rather than thought out.

Social Pressure and Individual Conduct

Guthrie examines how social pressure shapes ethical judgments. He reasons that the strongest injunctions correspond to fundamental requirements of existence, such as the sacredness of life within the community. Family relationships come next, followed by safeguards of property. In early stages, the coward is condemned while the warrior who protects the community is praised. Guthrie emphasizes that actions receive praise or blame according to whether they conduce to the welfare or suffering of the existing community. He illustrates this with Spencer's own data, citing that beyond refraining from direct and indirect injuries, there are spontaneous efforts to further others' welfare. This social pressure ensures that individual actions align with societal welfare.

The Ethical Imperative and Mutual Claims

Guthrie defines the ethical imperative as the claim of duties towards other individuals upon the ego, with mutuality of claim. He writes that the principle can be accepted as theoretically correct, and many general rights and duties can be deduced as corollaries. However, beyond these general rules, ethical problems are worked out through multitudinous adjustments and re-adjustments by individuals and societies. He gives the example of an individual contravening accepted social law: the individual is condemned and coerced into conformity, or society modifies its opinion in acknowledgment of the individual's right. Guthrie then raises the question of the principle upon which ethical judgments should be formed, given that society demands certain actions and prohibits others with the aim of biological completeness of individuals.

Guthrie's critique is tightly focused on the logical structure of Spencer's system, not on appraising the separate value of Spencer's works. Readers approaching this volume should have Spencer's Data of Ethics at hand, as Guthrie presupposes detailed familiarity. The argument proceeds by challenging the order of reasoning, not the empirical content. Pay attention to how Guthrie distinguishes between a priori deduction and a posteriori evidence, as this distinction underpins his entire criticism.